| ultrasonography, doppler, duplex | Ultrasonography applying the doppler effect combined with real-time imaging. The real-time image is created by rapid movement of the ultrasound beam. A powerful advantage of this technique is the ability to estimate the velocity of flow from the doppler shift frequency. (12 Dec 1998) |
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| ultrasonography, doppler, pulsed | Ultrasonography applying the doppler effect, with velocity detection combined with range discrimination. Short bursts of ultrasound are transmitted at regular intervals and the echoes are demodulated as they return. (12 Dec 1998) |
| ultrasonography, doppler, transcranial | A non-invasive technique using ultrasound for the measurement of cerebrovascular haemodynamics, particularly cerebral blood flow velocity and cerebral collateral flow. With a high-intensity, low-frequency pulse probe, the intracranial arteries may be studied transtemporally, transorbitally, or from below the foramen magnum. (12 Dec 1998) |
| foetal doppler study | <radiology> Non-stress test (NST), external monitoring for 20 minutes; poor specificity, greater than4 foetal heart accelerations (greater than15 bpm over baseline for 15 seconds) following foetal movement in foetus greater than34 weeks, no heart accelerations in immaturity, sleep, maternal sedation contraction stress test (CST), external monitoring after oxytocin or maternal breast stimulation, greater than 3 uterine contraction in 10 minutes; 50% specificity uterine and umbilical artery waveform, elevated systolic:diastolic ratio = increased vascular resistance foetal aortic flow volume, 185-246 ml/kg/min see also: biophysical profile, intrauterine growth retardation (IUGR) (12 Dec 1998) |
| laser-doppler flowmetry | A method of non-invasive, continuous measurement of microcirculation. The technique is based on the values of the doppler effect of low-power laser light scattered randomly by static structures and moving tissue particulates. (12 Dec 1998) |
| abscopal effect | A reaction produced following irradiation but occurring outside the zone of actual radiation absorption. (05 Mar 2000) |
| additive effect | <biochemistry, chemistry> An additive effect is the overall biological effect two chemicals acting together and which is the simple sum of the effects of the chemicals acting independently. Compare: antagonism. (15 Jan 1998) |
| adverse effect | This is an abnormal or harmful effect to an organism caused by exposure to a chemical. It is indicated by some result such as death, a change in food or water consumption, altered body and organ weights, altered enzyme levels, or visible illness. An effect may be classed as adverse if it causes functional or anatomical damage, causes irreversible change in the homeostasis of the organism, or increases the susceptibility of the organism to other chemical or biological stress. A non-adverse effect will usually be reversed when the organism is no longer being exposed to the chemical. (09 Oct 1997) |
| Anrep effect | A small transient positive inotropic effect of abrupt increases of systolic aortic and left ventricular pressures related to recovery from transient subendocardial ischemia (e.g., cold pressor test). (05 Mar 2000) |
| antagonistic effect | This is the consequence of one chemical (or group of chemicals) counteracting the effects of another chemical, the opposing chemicals cancel out each other's effects. (09 Oct 1997) |
| Arias-Stella effect | Focal, unusual, decidual changes in endometrial epithelium, consisting of intraluminal budding, and nuclear enlargement and hyperchromatism with cytoplasmic swelling and vacuolation; may be associated with ectopic or uterine pregnancy. Synonym: Arias-Stella effect, Arias-Stella reaction. (05 Mar 2000) |
| Auger effect | <physics> Transition of an electron in an atom from a discrete electronic level to an ionised continuous level with the same energy. Synonym: autoionisation. (13 Jan 1998) |
| autokinetic effect | In psychology, the apparent drifting about of a small, fixed, spot of light which is being observed in a dark room. (05 Mar 2000) |
| Bernoulli effect | <physics> The decrease in fluid pressure that occurs in converting potential to kinetic energy when motion of the fluid is accelerated, in accordance with Bernoulli's law. Applied in water aspirators, atomisers, and humidifiers in which a gas is accelerated across the end of a narrow, fluid-filled orifice. (05 Mar 2000) |
| Bohr effect | <physiology> Decrease in oxygen affinity of haemoglobin when pH decreases or concentration of carbon dioxide increases. (18 Nov 1997) |